97 lines
2.2 KiB
C++
97 lines
2.2 KiB
C++
#include <cstddef>
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#include <deque>
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#include <iostream>
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#include <stdexcept>
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#include <tuple>
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#include <utility>
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#include <variant>
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#include <vector>
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#include <fstream>
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#include <intcode/intcode.hpp>
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using namespace intcode;
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namespace {
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using Packet = std::pair<ValueType, ValueType>;
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using Ethernet = std::deque<std::pair<std::size_t, Packet>>;
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auto BuildNetwork(Machine m) -> std::vector<Machine> {
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std::vector<Machine> machines;
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for (int i = 0; i < 50; i++) {
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machines.push_back(m);
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std::get<Input>(Step(machines.back())).pos = i;
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}
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return machines;
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}
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auto Interact(Ethernet & ethernet, Machine & m, std::optional<Packet> p) -> void {
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for(;;) {
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auto effect = Step(m);
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switch (effect.index()) {
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default:
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throw std::runtime_error{"unexpected halt"};
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case 0: // Input
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if (p) {
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std::get<Input>(effect).pos = p->first;
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std::get<Input>(Step(m)).pos = p->second;
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p = {};
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break;
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}
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std::get<Input>(effect).pos = -1; // no packet
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return;
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case 1: // Output
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auto d = std::get<Output>(effect).val;
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auto x = std::get<Output>(Step(m)).val;
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auto y = std::get<Output>(Step(m)).val;
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ethernet.push_back({d, {x,y}});
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break;
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}
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}
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}
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} // namespace
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auto main(int argc, char ** argv) -> int {
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if (2 != argc) { return 1; }
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std::ifstream fin {argv[1]};
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auto machines = BuildNetwork(Machine{ParseStream(fin)});
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auto ethernet = Ethernet{};
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std::optional<ValueType> part1;
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std::optional<ValueType> part2;
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std::optional<Packet> nat;
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for(;;) {
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if (ethernet.empty()) {
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if (nat) {
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if (nat->second == part2) { break; }
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part2 = nat->second;
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Interact(ethernet, machines[0], nat);
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} else {
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for (auto && m : machines) {
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Interact(ethernet, m, {});
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}
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}
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} else {
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auto [dest, p] = ethernet.front();
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ethernet.pop_front();
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if (dest == 255) {
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nat = p;
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if (!part1) { part1 = p.second; }
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} else if (dest < 50) {
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Interact(ethernet, machines[dest], p);
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} else {
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throw std::runtime_error{"bad destination"};
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}
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}
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}
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std::cout << "Part 1: " << *part1 << std::endl;
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std::cout << "Part 2: " << *part2 << std::endl;
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}
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